This invention relates to a magnetizing system for magnetizing a permanent magnet to any desired magnitude.
In order to charge magnetically or magnetize permanent magnets, there have been already known magnetizing systems of the type comprising a U-shaped iron core, a pair of magnetizing coils wound around two legs of the "U" and connected serially to each other to cumulatively produce magnetic fluxes on the legs when the coils are energized, a pair of opposite spaced magnetic pole pieces connected to the free ends of the legs, and a DC source connected across the serially connected magnetizing coils through a normally open switch. A steel workpiece to be magnetized is put on the opposite magnetic pole pieces to bridge them and the switch is closed to cause a current from the DC source to flow through the connected magnetizing coils so as to apply a magnetic field to a magnetic path including the iron core, the magnetic pole pieces and the steel workpiece. Under these circumstance, when the switch is opened to stop the flow of current through the magnetizing coils, the steel workpiece is magnetically charged. That is, a permanent magnet results. Upon this magnetizing, the magnetic field has generally had a field strength not less than that required for the steel workpiece to be magnetically saturated. Then, the permanent magnet thus magnetized is demagnetized in order to stabilize the magnetic characteristics thereof. To this end, the permanent magnet is spaced from the magnetic pole pieces and approaches the magnetic field as described above while the magnetic polarity is reversed from that provided upon the magnetization. The distance to which the permanent magnet approaches the magnetic field has previously relied upon both experiences and the sixth sense of the operator of the system. This has required great skill on the part of the operator and the technique has been poor in its efficiency.
Alternatively, the permanent magnet might be put in an AC demagnetizing field which is varying in its field strength.
After having been demagnetized as described above, the permanent magnet has been measured as to its magnetization value. If the permanent magnet has been insufficiently demagnetizied, as determined by that measurement, it has been necessary to re-demagnetize the magnet. On the contrary, if the permanent magnet has been excessively demagnetized, as determined by the above-noted measurement, then it has been necessary to re-magnetize and then re-demagnetize the magnet. As a result, conventional magnetizing systems such as outlined above have been poor in their workability and accuracy while requiring great skill based on the experience and the sixth sense of the operator.
Accordingly, it is an object of the present invention to provide a new and improved magnetizing system for automatically magnetizing a magnetic workpiece to be magnetized by employing a sensor for sensing the amount of magnetization of the magnetic workpiece.
It is another object of the present invention to provide a new and improved magnetizing system for magnetizing a magnetic workpiece to be magnetized with improved workability and efficiency and without relying on experience and the sixth sense of the operator, resulting in a high quality product.